DDA 33rd Meeting, Mt. Hood, OR, April 2002
Session 9. Other Solar Systems
Tuesday, April 23, 2002, 10:50am-12:10pm

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[9.01] Dynamical Fitting Procedures for Multiple Planet Systems

G. Laughlin (UC Santa Cruz)

Increasing numbers of multiple planet systems are emerging from the ongoing radial velocity surveys. We show that for many multiple planet systems, the approximation that the planets are orbiting on Keplerian ellipses is inadequate for the purpose of fitting the radial velocity data. We describe the application of a fully self-consistent method for determining the true configurations of multiple-planet systems from radial velocity data. Our code leverages planet-planet gravitational perturbations to produce dynamical fits that remove the \sin (i) degeneracy. The code is based on a genetic algorithm driving a Levenberg-Marquardt minimization routine. Application of this method to the GJ 876 system has revealed the true masses of the planets, and has located their configuration deep within the 2:1 resonance. The method has also found repeated application as additional multiple planet systems are found. We describe several specific systems, including HD 82943, \upsilon Andromedae, and HD 20675. In the case of HD 82943, we show that self-consistent fitting produces a variety of two and three planet systems which are equally consistent with the radial velocities. In the case of \upsilon Andromedae, we show that self-consistent fitting is now required to accurately fit the entire time baseline of observations. In the case of HD 20675, we show that the radial velocity data set indicates some probability that this star harbors a heavily interacting two planet system.

This work was funded by the NASA Origins of Solar Systems Program.

The author(s) of this abstract have provided an email address for comments about the abstract: laughlin@ucolick.org

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Bulletin of the American Astronomical Society, 34, #3
© 2002. The American Astronomical Society.